1. Field of the Invention
The present invention relates to a wavefront aberration measurement apparatus, an exposure apparatus, and a method of manufacturing a device.
2. Description of the Related Art
Japanese Patent Laid-Open Nos. 2005-183415 and 2004-271334 disclose measurement apparatuses which measure the aberration of an optical system to be measured (test optics) such as a projection optical system (projection optics). An exposure apparatus described in Japanese Patent Laid-Open No. 2005-183415 diffracts light transmitted through the optical system using a diffraction grating, extracts ±1st-order diffracted light beams using a mask member, and measures the wavefront aberration of the optical system based on shearing interference fringes generated by the extracted ±1st-order diffracted light beams. In contrast, Japanese Patent Laid-Open No. 2004-271334 discloses a measurement apparatus which measures the wavefront aberration of the optical system by individually measuring the wavefront aberration of the optical system, including a wavefront aberration attributed to elements other than the optical system, and the wavefront aberration attributed to elements other than the optical system, and calculating the difference between these two wavefront aberrations. The wavefront aberration attributed to elements other than the optical system is generally referred to as system error.
Unfortunately, conventional measurement apparatuses which measure the wavefront aberration of the optical system cannot simultaneously measure both a wavefront aberration attributed to elements other than the optical system and the wavefront aberration of the optical system, including the wavefront aberration attributed to elements other than the optical system. Under such circumstances, the conventional measurement apparatuses suffer from a problem whereby it cannot correct errors associated with a situation in which the aberration attributed to elements other than the optical system changes with time during the measurements of the two wavefront aberrations. In another case, because the arrangement of a measurement system differs between when the wavefront aberration is attributed to elements other than the optical system and when the wavefront aberration is in the path including the optical system, the conventional measurement apparatuses suffer from other problems such that the influence of a change in aberration is attributed to differences in environment and this, in turn, lead to measurement errors.